All of the above are fine. If both parties know that the review is about the code and not the author then tone is more or less irrelevant. I’d prefer something

All of the above are fine. If both parties know that the review is about the code and not the author then tone is more or less irrelevant. I’d prefer something like this: “I think we should extract this logic/code/etc into a separate function for better testing, less code duplication, and better maintainability.” You only have to say that a few times before you can use the short hand: “Extract this into a function.” because you stated reasons before.